In conventional calendered papermaking for providing papers used in printing, a fibrous web may be prepared from an aqueous solids mixture which may comprise wood pulp and/or synthetic fibers along with various additives. These additives may include paper pigment(s) such as calcium carbonate, clay, titanium dioxide, etc., as well as pigment binders such as modified starch, styrene butadiene rubber, polyvinyl acetate, vinyl acrylic, polyvinyl alcohol, etc. Other additives such as sizing agents, fillers, pigments, dispersants, viscosity modifiers, crosslinking agents, lubricants, etc., may also be included in preparing paper substrates.
In recent years, the use of ink-jet printing methods has been increasing at a rapid rate. Ink jet printing is a method for forming ink images on a paper substrate from deposited droplets of ink comprising dyes or pigments. This printing method enables high-speed and full-color printing to be achieved. In ink jet printing, the fine droplets of ink are sprayed or jetted from printing nozzles at a high speed so as to direct the ink droplets toward, and deposit these droplets on, the paper substrate to provide printed images on the paper substrate.
The ink used in ink jet printing may contain either dyes or pigments as print agents. In the case of inks comprising pigments, the ink may also be in the form of a pigment emulsion. The use of pigment emulsions in the ink may increase the dry time for the ink droplets deposited on the surface of the paper substrate, and may thus lead to, for example, smearing of the deposited ink droplets. Accordingly, coatings for the paper substrate have been developed to be more receptive to the ink deposited by inkjet printers.
In coating paper substrates to be more receptive to inks deposited by inkjet printers, the resulting coated papers printed with inkjet ink may be more susceptible to physical damage. For example, coatings applied to paper substrates to make them more receptive to inks deposited by inkjet printers tend to be more porous or water-swellable. That makes such porous, water-swellable coated paper substrates more vulnerable to damage resulting from contact with water. In the case of dye-based inks, such damage from post-imaging contact with water may take the form of, for example, smearing or smudging of the inkjet-printed image. Pigment-based-inks printed on such porous, water-swellable coated paper substrates may also be easily smudged or smeared by rubbing the still moist surface of the pigmented image on the coated paper substrate.